Collection of DNA is the taking of biological samples, ie blood and other tissues samples (Mountain 2011). During collection it is essential to avoid contamination, because the analysis techniques can determine very low amounts of DNA (Mountain 2011).
DNA extraction varies slightly depending on the origin of the DNA but the general procedure follows these basic steps; concentration of material by centrifuge, agitation to loosen cells, breaking the cells open to release the DNA and other cellular components, removal of other cellular components (proteins, RNA, etc) leaving the geneticist with a solution of DNA (Mountain 2011).
PCR allows the rapid replication of specific sequences in DNA, using human specific primers that negate any bacterial DNA present, which has permitted degraded samples to be used and analysed for DNA typing (McDonald & Lehman 2012). Watch the following DNA Fingerprinting video for more information on how PCR works.
2mm wire with attached DNA in solution
Chen et al. (2011) developed a method of collecting DNA samples that can be used in the field on fresh tissue and on cadavers that is rapid, simple and robust. By using a heated stainless steel wire to collect a DNA sample and then snipping off a small (2mm) piece for testing, consequently allowing DNA material to remain on the rest of the wire for easy storage, of up to at least six months with reliable results when fixed with isopropanol (Chen et al. 2011).
The development of DNA databases, during the mid to late 1990’s, has improved the ability of the forensic scientist to find a genetic match for the remains they are examining, although while many countries, including Australia, Canada, Japan, New Zealand, the United Kingdom and the United States of America, have developed their own databases there is no testing/analysing standardisation between countries (McDonald & Lehman 2012) this can make it difficult to get an accurate match from a different countries database.
Collection of DNA is the taking of biological samples, ie blood and other tissues samples (Mountain 2011). During collection it is essential to avoid contamination, because the analysis techniques can determine very low amounts of DNA (Mountain 2011).
DNA extraction varies slightly depending on the origin of the DNA but the general procedure follows these basic steps; concentration of material by centrifuge, agitation to loosen cells, breaking the cells open to release the DNA and other cellular components, removal of other cellular components (proteins, RNA, etc) leaving the geneticist with a solution of DNA (Mountain 2011).
PCR allows the rapid replication of specific sequences in DNA, using human specific primers that negate any bacterial DNA present, which has permitted degraded samples to be used and analysed for DNA typing (McDonald & Lehman 2012). Watch the following DNA Fingerprinting video for more information on how PCR works.
The development of DNA databases, during the mid to late 1990’s, has improved the ability of the forensic scientist to find a genetic match for the remains they are examining, although while many countries, including Australia, Canada, Japan, New Zealand, the United Kingdom and the United States of America, have developed their own databases there is no testing/analysing standardisation between countries (McDonald & Lehman 2012) this can make it difficult to get an accurate match from a different countries database.
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